篝火慢慢闷烧着，散发出淡淡的烟雾。

The bonfire ___smoulders gently, releasing wisps of smoke.

尽管他表面平静，但内心燃烧着对背叛的愤怒。

Though calm on the surface, anger ___smouldered within him over the betrayal.

尽管他们表面和好，但怨恨仍在心中暗燃。

Although they made up on the surface, resentment still ___smoulders in their hearts.